Definition of "let"
To allow to, not to prevent (+ infinitive, but usually without to).
To allow the release of (a fluid).
To allow possession of (a property etc.) in exchange for rent.
Used to introduce an imperative in the first or third person.
To cause (+ bare infinitive).
To hinder, prevent; to obstruct (someone or something).
To prevent or obstruct to do something, or that something happen.
An obstacle or hindrance.
The hindrance caused by the net during serve, only if the ball falls legally.